Replaceable seal members for butterfly valve

ABSTRACT

A butterfly valve having a valve body with a seat therein and a valve disc carried on a rotatable shaft such that the valve disc can be moved into and away from sealing engagement with the valve body seat is provided with a removable and replaceable seat member forming the valve body seat and a removable and replaceable sealing surface member is mounted on the valve disc which is sealingly engageable with the seat member when the valve disc is moved into sealing engagement with the valve body seat. The valve body seat preferably is sized to be press fit into a recess in the valve body and retained therein without additional fasteners. This butterfly valve can be used in a single, double or triple offset valve and the valve can be attached to a pipe in any conventional manner. The valve seat material and the sealing surface material may be solid metal, a resistant material such as nylon or Teflon®, may have a metal insert or may have a high temperature insert such as graphite.

This is a division, of application Ser. No. 08/542,435, filed Oct. 12,1995 now U.S. Pat. No. 5,707,040.

BACKGROUND OF THE INVENTION

The present invention relates to sealing members for butterfly valves,and more specifically to removable and replaceable valve sealingmembers.

Butterfly valves are well known wherein a valve body, which is generallya cylindrical member for allowing fluid to flow therethrough, has avalve seat formed therein and a movable valve disc is carried on arotatable shaft such that the valve disc can be moved into and away fromsealing engagement with the valve body seat. Thus, in such a valve thereare two sealing surfaces, one sealing surface is the valve seat in thevalve body, while the other sealing surface is carried on a periphery ofthe valve disc. When the disc is brought into contact with the seat, aseal is formed.

In one type of butterfly valve presently available, the valve seat isformed integrally with the valve body and the sealing member on thevalve disc is replaceable and is held onto the valve disc by a retainerring held in place by cap screws.

In another type of butterfly valve presently available, the valve disccomprises a single unitary member and a removable and replaceable sealmember is mounted to the valve body by means of a retaining ring held inplace in the valve body by cap screws. In this type of arrangement thecross sectional flow area through the valve body is reduced in order toprovide sufficient area for the cap screws to engage into the valve bodyand for the retaining ring to hold the ring-like seal member in place.

Butterfly valves can be used in a wide variety of installations within apipeline, wherein the pipeline may carry a wide range of differentfluids. In some instances the fluids may be corrosive or may have arelatively high temperature or relatively low temperature, and evenmight carry some solids. In the operation of a butterfly valve, due tothe fluid and material flowing through the valve body when the disc isin an open position, sometimes the sealing surfaces carried by the discor within the valve body becomes cut, scratched or damaged in some otherfashion. When this occurs it is necessary to repair the sealing surfacesin order to be assured that complete sealing will be provided. However,in present constructions it is possible to only replace one of the twosealing surfaces, thus preventing complete repairability of thebutterfly valve when both surfaces are damaged.

In order to provide enhanced sealing and reduced wear between themovable disc and the valve body seat, special geometries andconstructions are used. For example, in some constructions the valvedisc is carried on a shaft and the shaft rotates to move the discrelative to the valve body seat, however, the shaft is offsetlongitudinally (relative to the fluid flow centerline of the valve body)from the sealing area between the disc and the valve body seat. Thus, anaxis of rotation of the disc shaft is parallel to, but offset from, aplane in which the valve disc engages the valve body seat.

A second offset may be provided for the valve disc shaft. This secondoffset is a lateral offset such that although the axis of rotation ofthe valve shaft is perpendicular to the flow through centerline of thevalve body, the valve disc shaft is laterally offset so that its axis ofrotation does not intersect the centerline of the valve body.

Third, it has been found that by making the valve seat have afrusto-conical shape and having the valve disc have a complementaryfrusto-conical shape enhances the sealing characteristics of thebutterfly valve. A third offset is to incline the angle of thefrusto-conical shapes such that if the shape was projected out to anapex, the apex would be offset from the centerline of the valve body.

The valve bodies are connected at each end to a pipe forming a pipeline,and the connection can be one of a variety of different connectiontypes. For example, the pipe ends may be flanged and the valve body alsoflanged with a series of apertures therethrough for receiving mountingbolts to secure the valve body within the pipeline. Alternatively,instead of a full flange, a series of angularly spaced lugs may beprovided around the periphery of each end of the valve body to alignwith similar lugs or a flange on the pipe for receiving securing bolts.Also, the valve body may be a wafer style which is relatively thin andwhich is positioned between flanges in the pipe and is clamped betweenthe flanges. Further, the valve body may be arranged to be welded to thepipe or even threaded to the pipe.

SUMMARY OF THE INVENTION

The present invention provides for an improved butterfly valveconstruction wherein the seat in the valve body has a removable andreplaceable ring shaped seat seal member and also the valve disc isprovided with a removable and replaceable ring shaped sealing surfacemember such that either sealing member, or both, may be removed andreplaced as needed either to repair each of the sealing members due todamage or to allow changing the sealing member materials to suitparticular pipeline conditions. Sometimes it becomes apparent after thepipeline has been in service for a while that the seat materialsoriginally selected are not appropriate for the fluid being directedthrough the pipeline. By use of the present invention, the user mayreplace both sealing members with a more corrosive resistant material ora sealing member suitable for higher or lower temperature service as isnecessary.

The present invention also allows the use of seat materials both in thevalve body and on the valve disc that are not weldable type materials orthat are not weld compatible with the valve body material. Also, thepresent invention allows for the use of resilient inserts such as nylon,Teflon®, etc. for solid metal seats and also for seats with metalinserts or high temperature material such as graphite. Thus, the presentinvention allows for a wide range of flexibility in material selectionand replacement and can be used in any type of butterfly valveconstruction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a butterfly valve embodying theprinciples of the present invention.

FIG. 2 is a partial side sectional view of the valve seat area of thevalve of FIG. 1.

FIG. 3 is a partial side sectional view of the valve seat area as anFIG. 2, showing an optional sealing insert.

FIG. 4 is a plan view of a pipeline with a butterfly valve therein andillustrating three offsets.

FIG. 5 is an end elevational view of a butterfly valve embodying theprinciples of the present invention utilizing a flanged valve body.

FIG. 6 is an end elevational view of a butterfly valve embodying theprinciples of the present invention utilizing a lugged valve body.

FIG. 7 is an end elevational view of a butterfly valve embodying theprinciples of the present invention utilizing a wafer style valve body.

FIG. 8 is an end elevational view of a butterfly valve embodying theprinciples of the present invention utilizing a weldable or threadablevalve body.

FIG. 9 is a partial sectional view of a butt weld connection between avalve body and a pipe.

FIG. 10 is a partial sectional view of a socket weld connection betweena valve body and a pipe.

FIG. 11 is a partial sectional view of a threaded connection between avalve body and a pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 there is illustrated a butterfly valve generally at 20 whichis comprised of a valve body 22 and a movable valve disc 24. The valvedisc 24 is carried on a rotatable shaft 25. The valve body 22 isprovided with a removable and replaceable seat member 26 which is sizedto be press fit into a recess 28 and against a shoulder 30 in the valvebody and retained therein without additional fasteners. The seat member26 preferably is a one piece ring shaped member, although it may have aninsert as described in more detail below.

The valve disc 24 is provided with a ring shaped removable andreplaceable sealing surface member 32 which is held onto the disc bymeans of a retaining ring 34 which is secured by cap screws 36 into thevalve disc 24. The retaining ring 34 presses the sealing surface member32 against a gasket 38 so that there is no leakage occurring between thesealing surface member 32 and the disc 24. The valve shaft 25 isjournaled in the valve body 22 by use of bushings 40 and sealed bypacking 39 and gasket 41 to avoid any leakage at the valve shaft.

As best seen in FIG. 2, typically the seat member 26 has afrusto-conical shape and presents an angled surface 42 facing toward thedisk 24. Also, the sealing surface member 32 has a complementaryfrusto-conical shape such that when the disc 24 is closed intoengagement with the valve body 22 the two angled surfaces will wedgetogether to form a tight seal area.

The seat member 26 and the sealing surface member 32 may be formed froma variety of materials to accommodate particular fluids and temperaturesof fluids flowing through the valve body 22, such as a resilientmaterial like synthetic rubber, nylon or Teflon®, or a solid metalmaterial formed of a particular metal which, in some instances, may needto be resistant to corrosive characteristics of the fluid. Also, asshown in FIG. 3, the valve seat member 26 may be provided with an insert44 such as a resilient material like synthetic rubber, nylon or Teflon®or a high temperature material like graphite or a metal insert retainedwithin a different metal material forming the seat member 26. Thus, awide range of conditions may be accommodated by selecting theappropriate material for the seat member 26 and the sealing surfacemember 32. Also, both of these sealing members 26, 32 can be removed andreplaced if conditions of the fluid carried through the valve body 22change or if it is determined after an initial operating period thatdifferent materials would be more suitable for use in connection withthe fluids being directed through the valve body, in addition to beingchanged or replaced due to damage to either or both members.

In order to enhance the sealing characteristics of the butterfly valve20 and to reduce wear and rubbing action between the valve body seatmember 26 and the sealing surface member 32, it may be desirable toprovide one, two or even three offsets. These offsets are illustrated inFIG. 4. There it is seen that the valve shaft 25 has an axis of rotation50 which is offset by a distance A from a plane 52 passing through thesealing engagement area between the valve seat member 26 and the sealingsurface member 32. A second offset is shown wherein the axis of rotation50 is offset laterally by a distance B from a centerline 54 of the valvebody such that, although the axis of rotation 50 is perpendicular to thevalve body centerline 54, they do not intersect.

A third offset is shown which relates to the frusto-conical shape of thevalve seat member 26 wherein, when the conical shape is projected out toan apex 56, that apex is offset by a distance C from the centerline 54of the valve body 22. The present invention accommodates any one or anycombination of these offsets. If the third offset is utilized, then theangle of the inwardly directed face 42 of the valve seat member 26changes in relation to the sidewall of the valve body 22 around thecircumference of the seat member 26. This same changing angle iscomplemented by the sealing surface member 32. Thus, these two sealingmembers must be mounted into the valve body 22 and onto the valve disc24, respectively, in the appropriate angular position so that the twoangled mating surfaces will be properly aligned. This angularpositioning may be accomplished by means of recesses and detents,markings or other alignment features.

The present invention can be utilized in any style of valve bodyavailable. For example, FIG. 5 illustrates a butterfly valve body 22Ahaving a full flange 60 with a series of angularly spaced holes 62therethrough. As shown in FIG. 1, such an arrangement is provided sothat the flange 60 will abut with a flange 64 on a pipe 66. Such flange64 also is apertured so that a clamping bolt 68 can hold the two flangestogether with a sealing gasket 70 interposed therebetween.

FIG. 6 illustrates a somewhat similar valve body 22B which, instead of afull flange, contains a series of angularly spaced lugs 72 which haveholes 74 therethrough, again for receiving fastening bolts from a pipe.In this type of arrangement the valve body 22B may have a relativelyshort axial dimension along its flow centerline 54 such that the lugs 72are clamped between adjacent end flanges in the connecting pipes.

FIG. 7 illustrates a wafer style valve body 22C in which the axiallength of the valve body is short and the valve body is sandwichedbetween two flanged pipe ends. A single bottom lug 76 is provided andholes 78 are provided at the top and bottom of the valve body 22C forreceipt of clamping and aligning bolts from the pipe flanges.

FIG. 8 illustrates a valve body 22D that is designed to be connected toadjacent pipes either by welding or by a threaded connection.

FIG. 9 illustrates a butt weld between a valve body wall 22D and a pipewall 66D. The ends of the two walls are beveled to receive the weldmaterial 80. A second type of weld connection is illustrated in FIG. 10which is referred to as a socket weld in which a pipe 22E is received ina socket in a valve body 66E and weld material 82 holds the two wallstogether.

FIG. 11 illustrates a threaded connection between a valve body wall 66Fand a pipe wall 22F.

As is apparent from the foregoing specification, the invention issusceptible of being embodied with various alterations and modificationswhich may differ particularly from those that have been described in thepreceding specification and description. It should be understood that Iwish to embody within the scope of the patent warranted hereon all suchmodifications as reasonably and properly come within the scope of mycontribution to the art.

I claim as my invention:
 1. A butterfly valve having a valve body with avalve seat therein and a valve disc assembly carried on a rotatableshaft such that said valve disc assembly can be moved into and away froma sealing engagement position with said valve seat, said valve bodydefining a longitudinal centerline:wherein said valve seat comprises aremovable and replaceable seat member; and said valve disc assemblycomprises a valve disc and a removable and replaceable sealing surfacemember mounted on said valve disc which is sealingly engageable withsaid seat member when said valve disc assembly is moved into saidsealing engagement position with said valve seat; wherein said seatmember is formed in a frusto-conical shape on an inside surface thereofand said sealing surface member has a complementary frusto-conicalshape, said frusto-conical shape, when projected to an apex, defining anapex point offset from said longitudinal centerline of said valve bodyand offset by a radial distance from said longitudinal centerline ofsaid valve body less than a largest inside radius of said seat member.2. A butterfly valve according to claim 1, wherein said seat member issized to be press fit into a recess in said valve body and retainedtherein without additional fasteners.
 3. A butterfly valve according toclaim 1, wherein an axis of rotation of said rotatable shaft is parallelto but offset from a plane in which said valve seat is engaged by saidsealing surface member.
 4. A butterfly valve according to claim 3,wherein said valve body is cylindrical and has a longitudinalcenterline, and said rotatable shaft is perpendicular to and offset fromsaid longitudinal centerline such that an axis of rotation of said shaftdoes not intersect said longitudinal centerline.
 5. A butterfly valveaccording to claim 1, wherein said valve body comprises a wafer stylebody.
 6. A butterfly valve according to claim 1, wherein said valve bodyhas a plurality of apertured lugs formed thereon to mate withcorresponding apertures on a flange of a pipe to be connected to saidvalve body.
 7. A butterfly valve according to claim 1, wherein saidvalve body has a flange thereon with holes therethrough to mate with acomplementarily apertured flange on a pipe to be connected to said valvebody.
 8. A butterfly valve according to claim 1, wherein said valve bodyhas an end thereon configured to be butt welded to a pipe to beconnected to said valve body.
 9. A butterfly valve according to claim 1,wherein said valve body has an end thereon configured to be socketwelded to a pipe to be connected to said valve body.
 10. A butterflyvalve according to claim 1, wherein said valve body has a threaded endto mate with a complementarily threaded pipe to be connected to saidvalve body.
 11. A butterfly valve according to claim 1, wherein at leastone of said seat member and said sealing surface member comprise aresilient material wherein said resilient material is selected from thegroup consisting of nylon and Teflon®.
 12. A butterfly valve accordingto claim 1, wherein at least one of said seat member and said sealingsurface member comprises solid metal.
 13. A butterfly valve according toclaim 1, wherein at least one of said seat member and said sealingsurface member comprises a metal insert.
 14. A butterfly valve accordingto claim 1, wherein at least one of said seat member and said sealingsurface member comprises a high temperature insert consisting ofgraphite.
 15. A butterfly valve according to claim 1, wherein said seatmember comprises a resilient insert wherein said resilient insert is amaterial selected from the group consisting of nylon, rubber andTeflon®.
 16. A butterfly valve according to claim 1, wherein said seatmember comprises a metal insert.
 17. A butterfly valve according toclaim 1, wherein said seat member comprises a high temperature insertconsisting of graphite.